I appreciate this product and my client has decided to migrate this tool with his website. So, I would like to know if that's possible. Website is developed in PHP language. I will wait for your positive feedback.
I've checked the system requirements for this application and it doesn't appear to be available for integration with websites. The system requirements say that you can install it on Windows or Mac, but nothing mentioned about web servers or PHP language supported.
However, you should address this to the developers and they might provide a solution for this inquiry: http://www.invisalign.com/contact-us